Streak cameras are known and comprise a versatile light detection instrument giving temporal information. Streak cameras have been used to measure electron bunches in synchrotrons, fast (femtosecond) laser pulses and plasma physics experiments.
Reference is made to IEEE transactions on Nuclear Science Vol. 47, No. 6, December 2000, p. 1753. Typically, in a streak camera pulsed incident light is converted to electrons by a photocathode. The electrons are then accelerated by a mesh electrode before the electrons pass between two parallel plate electrodes that have a temporally varying sweep voltage applied to them such that the electrons receive a deflection before they impinge upon a phosphorescent screen.
The signal from the screen is read by a position sensitive detector.
According to the known arrangement the position of the signal on the screen is directly related to the instantaneous sweep voltage that the electrons encountered when the electrons passed rapidly through or between the deflection plates. Temporal information is therefore converted to spatial information. Depending upon the application this reduces the requirements placed on the high speed digitising electronics used to capture the signal and/or increases the overall temporal resolution of the device.
The streak camera principle has been applied to Time of Flight detection of heavy ions in the radioactive ion beam facility at RIKEN (IEEE transactions on Nuclear Science Vol. 47, No. 6, December 2000, p. 1753). Two streak cameras were used to register secondary electrons produced by a heavy highly energetic ion passing through thin metallic films. The known device employed 100 MHz sinusoidal waveforms to deflect the beam in x and y dimensions onto a phosphor screen. The phosphorescence was then amplified and captured by a charged coupled device (“CCD”).
The principle has also been applied to Time of Flight mass spectrometry whereby a ramp voltage is synchronized to the frame rate of a sensor that is set at about 20 MHz (bin width about 50 ns). Reference is made to WO 2012/010894 (ISIS).
As digital electronics gets faster so does the digitisation frequency of Time to Digital Converters and Analogue to Digital Converters which means that the deflection plates must sweep at a correspondingly faster rate.
Fast pixelated detectors having a bin width of about 100 ps are being developed to detect ions in systems using a microwave cavity resonator to sweep an electron beam across the surface of the fast pixelated detector. Such very fast detectors typically have a moderate number of pixels, a relatively large pixel size (e.g. about 0.5 mm) and operate in a time to digital conversion mode i.e. one bit of vertical information. To produce an intense electric field to sweep electrons for streak cameras in synchronization with state of the art digitizers capable of running at bin widths of typically about 100 ps or faster is challenging and expensive.
It is desired to provide an improved pixelated detector such that the maximum amount of data can be captured.
It is also desired to provide an inexpensive pixelated detector that is able to handle large amounts of data.